1. Field of the Invention
The invention relates to a method for preparing plastic waste composed of different plastics, possibly in combination with other materials, for further processing as well as a device for preparing plastic waste composed of different plastics, possibly in combination with other materials, for further processing.
2. Description of the Prior Art
Today waste is collected so that so-called valuable materials are placed in a container in the homes and other materials which can decompose and rot or are heavily contaminated are placed in another container.
The valuable materials can likewise be readily contaminated. They consist of a wide variety of plastics, such as polyethylene, polypropylene, polystyrene, PVC, etc., cardboard, paper, metal, possibly other forms of cellulose, etc. At a waste collection site, the basically different materials are separated and sorted, namely plastics on the one hand, and cardboard and large metal objects on the other.
In addition, a fine sorting of the different plastics is also provided in part, especially when there is a demand for special recyclable plastics such as polypropylene or the like, and a very special type of plastic can be deliberately sorted out without great expense, yogurt containers for example.
However, many objects made of a wide variety of plastics that are easily contaminated remain in the plastic waste or in the plastic fraction, and may be combined with other materials such as the remaining metal lids of yogurt containers of the like. Further separation and sorting is often not possible for technical reasons, and in part is either not desirable or not feasible for economic reasons.
In the past, these plastics which could not be separated further, prepared, or processed, and often contained foil, plastic bags, etc., were baled and stored as such temporarily at the waste collection site. Intermediate storage in bales entails considerable risks, since spontaneous combustion can occur very easily and in at least one specific case it has happened that plastic bales stored in precisely this manner caught fire. As a result, particularly if the plastic waste contains PVC, dioxin can be released in the fire.
Another disadvantage of immediately subsequent intermediate storage in plastic bales consists in the fact that the contaminated material compressed into the bales is not biologically inert. Bacteria work in the components of the contamination and cause the bales to expand and their volume to increase, even causing the wraps to burst.
The problems recited above result partly from the fact that this plastic material does not accumulate more or less continuously or semi-continuously, but that it arrives at a collection point on one or at most two days a week or every fourteen days, but for logistical reasons must be processed further immediately even if it is only for intermediate storage in the form of plastic bales or in some other fashion. In addition, the volume of waste accumulating at a collection point is often so small that stationary processing machinery, such as regranulating machinery, is used for only a short time, namely a few hours, since there is not sufficient waste volume available to use such machinery over the entire work time of a week or fourteen days until the next day on which the corresponding waste containing valuable materials arrives.